The fast top runner was hiding xsim stdout in /tmp and only echoing PASS/FAIL,
which buried the TB $display diagnostics needed when a case fails. Now xsim
output is tee'd to both terminal and log, with the PASS/FAIL summary appended.
./run_tb.sh top [K] [CASE] now elaborates only the requested K and runs only
the requested CASE(s), parsing PASS/FAIL + file-not-found per run. Avoids the
full 3-snapshot, 11-case sweep when iterating. 'top' with no extra args and
all other modules keep their original full-tcl behaviour.